Investigation of the Effect of Age on Assimilation of Leaves

Singh, B. N.; Lal, K. N.

doi:10.1093/oxfordjournals.aob.a090507

Cited by 51 publications

(14 citation statements)

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“…It is evident, however, that the photosynthetic capacity of the leaves decreases with increasing age beginning during the second year. These data are in accord with those published by SINGH and LAL (2) who reported that the maximum photosynthetic capacity was attained in some angiosperms at the time of apparent leaf maturity. The results do not confirm the conclusion of ST.LFELT (3) that the rate of photosynthesis increases with increasing age of needles up to three and five years for pine and spruce, respectively.…”

Section: Methodssupporting

confidence: 93%

“…The literature on this subject appears to be rather meager. SINGH and LAL (2) working with different aged leaves of flax, sugar cane, and wheat found that the rates of photosynthesis were slow for young leaves, increased to a maximum for mature leaves, and then decreased with increasing age. From studies on aging effects in Chlorella cultures, WINOKUR (5) reported that the rate of photosynthesis, expressed either per unit number of cells or per unit dry w-eight, increased during the first few days of a culture and then declined with increasing age of the culture.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Age of Leaves Upon the Rate of Photosynthesis in Some Conifers

Freeland

1952

Plant Physiol.

107

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Section: Methodssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Effect of Age of Leaves Upon the Rate of Photosynthesis in Some Conifers

Freeland

1952

Plant Physiol.

107

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“…This decline in the rates of ATP synthesis was paralleled by the decline in the rate of C02 fixation. The results suggest that the efficiency of the membrane-bound ATP synthesizing system declines with age.Photosynthetic and respiratory rates vary with leaf age (8,13,14,22,23,26). In leaves of dicotyledon plants after an initial rise (3), the photosynthetic capacity gradually declines after leaf expansion (6,16,19,20 …”

mentioning

confidence: 99%

Functional and Structural Changes in Senescing Populus deltoides (Bartr.) Chloroplasts

Hernández-Gil¹,

Schaedle²

1973

Plant Physiol.

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Chloroplasts isolated from Populus deltoides leaves were used to study age-dependent changes in the rate of cyclic photophosphorylation. Single leaves were used to measure C02 fixation by leaf discs, chlorophyll concentration, and ATP synthesis. The ability of chloroplasts to synthesize ATP diminished steadily from the time of full leaf expansion, regardless whether the results are expressed on a leaf area or chlorophyll basis. This decline in the rates of ATP synthesis was paralleled by the decline in the rate of C02 fixation. The results suggest that the efficiency of the membrane-bound ATP synthesizing system declines with age.Photosynthetic and respiratory rates vary with leaf age (8,13,14,22,23,26). In leaves of dicotyledon plants after an initial rise (3), the photosynthetic capacity gradually declines after leaf expansion (6,16,19,20

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“…Flow rates were adjusted to give about 1.5 changes of C02-free air per minute. The soda-lime column was changed every 24 hours.…”

mentioning

confidence: 99%

Factors Influencing Abscission.

Biggs¹,

Leopold²

1957

Plant Physiol.

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The hormonal concept of abscission control was spearheaded by the suggestive experiments of Laibach in 1933 (15) and then more specifically established by the experiments of La Rue (17) in which he found that indoleacetic acid, pollen extracts, or urine could delay the abscission of debladed petioles. Since that time, numerous reports have added substantial support to the idea that auxins control abscission through an inhibitory influence (1,10,19, 25). More recently the concept of hormonal control has been extended to include auxin promotion of abscission as well (1,11).A useful tool for studying the effects of various substances on abscission has been the petiole explant test described by Addicott et al (4). This test with modification has been used subsequently by a number of workers: by Livingston (18) to study the effects of ethylene, sucrose, and auxins on abscission; by Carns (6) to study the influence of metabolic inhibitors; by Osborne (21) to seek a natural factor which promotes abscission; and by Gaur and Leopold (11) to study the quantitative effects of auxin on abscission.It has been observed in this laboratory that explant tests performed under similar conditions but at different times showed a considerable degree of variation and in fact in some tests no abscission occurred at all. The following experiments were undertaken to establish a more reliable explant test and to clarify some of the factors influencing abscission. Interactions between leaf age, substrates, light and auxin are described.MATERIAL AND METHODS Seedlings of Phaseolus vulgaris L. var. Red Kidney, were grown in flats in the greenhouse on a 16-hour-day. Daylength was extended with incandescent lamps giving approximately 70 ft-c at plant level.Explants 1 cm in length were taken from the primary leaves to include 5 mm of petiole and 5 mm of pulvinus tissue. These explants were placed in 5-cm Petri dishes, basal end down, to a 4-mm depth in 1 % agar with or without addenda. There were 20 explants per treatment. Each experiment reported here was repeated in its entirety at least 3 times and the results are consistent with 35 other experiments encompassing variations on these reported ones. Napthaleneacetic acid (NAA) was incorporated into the agar as its ammonium salt. No organic solvent was used to dissolve the auxin.Light treatments given to the explants involved a 12-hr day w ith 300 ft-c light intensity supplied by

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Investigation of the Effect of Age on Assimilation of Leaves

Cited by 51 publications

References 0 publications

Effect of Age of Leaves Upon the Rate of Photosynthesis in Some Conifers

Effect of Age of Leaves Upon the Rate of Photosynthesis in Some Conifers

Functional and Structural Changes in Senescing Populus deltoides (Bartr.) Chloroplasts

Factors Influencing Abscission.

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